In the 3rd Generation Partnership Project (3GPP), a radio access method and a radio network for cellular mobile communications (hereinafter, referred to as “Long Term Evolution (LTE: registered trademark)”, or “Evolved Universal Terrestrial Radio Access (EUTRA)”) have been studied. In LTE, a base station apparatus is also referred to as an evolved NodeB (eNodeB), and a terminal apparatus is also referred to as a User Equipment (UE). LTE is a cellular communication system in which multiple areas covered by the base station apparatuses are deployed to form a cellular structure. A single base station apparatus may manage multiple cells.
In LTE release 13, career aggregation which is a technique for a terminal apparatus to perform simultaneous transmission and/or reception in multiple serving cells (component careers) has been specified (Non Patent Literature 1, 2, 3, 4, and 5). In LTE release 14, function enhancement of Licenses Assisted Access (LAA) and carrier aggregation using uplink carriers in an unlicensed band has been studied (Non Patent Literature 6). Also in Non Patent Literature 6, transmission of a Physical Random Access CHannel (PRACH) using an uplink carrier in an unlicensed band has been studied.